Prevalence of sequences of probable clusters of agarolytic genes in streptomycetes

Aim. Polysaccharide agarose is an important component of the cell walls of red algae. The ability to depolymerize agarose by streptomycetes was first detected in the Streptomyces coelicolor A3(2) strain. For a long time, this streptomycete was considered the only representative of the genus capable of fermenting agarose. The pathway of agarose fermentation by the strain has been studied, and the genes determining the enzymes necessary for this process have been identified. These genes are collected in a cluster located on the chromosome. To identify streptomycetes whose genomes contain sequences similar to the agarolytic gene cluster of S. coelicolor A3(2) and to establish the genetic relatedness of the identified streptomycetes. Methods. We analyzed information on the primary structures of streptomycete genomes in databases on the NCBI server. During the research, we used a bioinformatic research method (BLASTN program) on the NCBI server. The nucleotide sequences of the agarolytic cluster and 16S rRNA of the S. coelicolor A3(2) strain were used as queries in the BLASTN analysis. Results. At present, only 0.12% of sequenced streptomycete genomes have sequences similar to the aga-cluster of S. coelicolor A3(2). It was established that probable agarolytic clusters are widespread in the genomes of genetically unrelated streptomycetes. Conclusions. The ability to depolymerize the polysaccharide agarose occurs much more frequently in streptomycetes than previously thought.